1. Field of the Invention
The present invention relates to a photosensitive resin composition which can be effectively used in forming a fine resist pattern. This photosensitive resin composition is called a photoresist and is widely used in a planar processing by photolithography such as a manufacturing process of a semiconductor device.
2. Description of the Prior Art
In order to realize a multifunction and high performance of an electronic device such as an LSI, an integration degree and a packing density of an electronic device have been greatly increased. In order to achieve a high packing density, an improvement in photolithography for enabling micropatterning is the most significant subject.
One factor of the photolithography is etching. For this reason, dry etching such as reactive ion etching (RIE) suitable for micropatterning is widely used.
Another factor of the photolithography is a photoresist. In order to realize micropatterning, a photoresist must satisfy the following two requirements.
First, a resist pattern which is sufficiently fine to achieve micropatterning and high packing density of a device can be formed by exposure and development. This resist pattern consists of a number of resist lines having a predetermined width and thickness and spaces between the resist lines. Therefore, in order to satisfy this requirement, resolution of the photoresist must be increased further.
Second, each resist line formed by exposure and development must have a high heat resistance sufficient as an etching mask for RIE. If the heat resistance is not sufficient, the resist lines deform during RIE. For example, even if the line initially has a sharp edge shape, a slope having a round edge portion is formed. When such deformation occurs, pattern transfer cannot be correctly performed to an underlying substrate by etching.
In order to satisfy the above requirements, Japanese Patent Publication No. 52-29261 discloses a photoresist consisting of a homopolymer or copolymer of vinylphenol or derivative thereof and a photosensitive reagent. However, although a resist pattern formed by this conventional photoresist has a high heat resistance, its resolution is not sufficient. For this reason, this photoresist cannot be used for manufacturing a highly-integrated LSI which must have a design rule of about 0.8 .mu.m.